Motor vehicle headlights having a plastic reflector and lens secured thereto have been recently introduced and provide several advantages over existing headlights wherein the reflector and lens components are comprised of glass. Examples are shown in U.S. Pat. Nos. 4,344,120 (Bradley et al), 4,342,142 (Nieda et al), 4,280,173 (Bradley et al), 4,210,841, (Vodicka et al) and 4,181,869 (Warren et al). One particular advantage of a plastic headlight wherein a tungsten-halogen capsule is utilized as the light source is a significant savings in weight. For example, a savings of approximately three pounds over a standard glass, four headlight system has been realized when using four corresponding plastic headlights. In addition, it has been determined that a plastic lens transmits from about ten to about fifteen percent more light than a glass lens because it is possible to mold a plastic (e.g., polycarbonate) lens with sharper (more precise) optics than is possible when molding glass. In addition to the above, plastic headlamps utilizing a tungsten-halogen capsule as the light source have been shown to save approximately five amperes of electricity when operated in the low beam mode.
During manufacture of plastic headlights of the type described above (those having a tungsten-halogen capsule), it is necessary to firmly position the capsule within the headlight relative to the reflector's internal reflecting surface. This is typically done by utilization of at least two (and sometimes three) support wires which in turn are connected to the lamp capsule, either to the lead-in wires extending from the capsule or to a suitable conductive retainer fitted over the capsule's press-sealed end. The support wires in turn penetrate the rear portion of the reflector through a corresponding plurality of openings located therein. A metallic eyelet member is often inserted within the opening and joined to a corresponding metallic lug member located externally of the reflector and designed for providing electrical connection to an external source (e.g., an electrical connector forming part of the motor vehicle's wiring system). One specific example of such an arrangement is the headlight shown and described in the aforementioned U.S. Pat. No. 4,181,869 (Warren et al), said patent assigned to the same assignee as the instant invention.
Also during the above assembly, an adhesive such as an epoxy resin in a paste-like or semi-liquid form is dispensed into the described openings in the rear of the plastic reflector in order to provide improved sealing of the reflector to the aforementioned metallic lug and eyelet. Because of manufacturing variations in the size of the reflector's openings which are to be filled, as well as manufacturing variations in the assembly process, the proper amount of adhesive necessary to fill the respective openings varies from lamp to lamp. During the manufacturing process, to be safe, it is thus preferred to dispense more (excess) adhesive than might be needed. Therefore, when the lug is fastened to the eyelet, the excess adhesive is often squeezed out to the outside edges of the lug and occasionally onto the back surface of the reflector. This in turn causes problems both in handling and additional processing of the headlight through the remainder of the assembly procedure. For example, there can often be a charring of the excess adhesive which occurs during a subsequent soldering step, resulting in an unsightly appearance of the finished product. In addition, excess adhesive can cause "bad solder" defects due to its presence on surfaces of the lug and/or eyelet which eventually receive the solder employed on headlights to secure the headlight's lead-in support wire relative to the eyelet and contact lug members.
It is believed, therefore, that a motor vehicle headlight which incorporates therein a new and unique means for accommodating for excess adhesive used during manufacturing thereof would constitute an advancement in the art.